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fuchsia / third_party / swift / 270ad33a72e7e46e5145174e704a9039167dd084 / . / lib / SILOptimizer / Utils / Local.cpp
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//===--- Local.cpp - Functions that perform local SIL transformations. ----===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#include "swift/SILOptimizer/Utils/Local.h"
#include "swift/SILOptimizer/Utils/CFG.h"
#include "swift/SILOptimizer/Analysis/Analysis.h"
#include "swift/SILOptimizer/Analysis/ARCAnalysis.h"
#include "swift/SILOptimizer/Analysis/DominanceAnalysis.h"
#include "swift/AST/GenericSignature.h"
#include "swift/AST/SubstitutionMap.h"
#include "swift/SIL/DynamicCasts.h"
#include "swift/SIL/SILArgument.h"
#include "swift/SIL/SILBuilder.h"
#include "swift/SIL/SILModule.h"
#include "swift/SIL/SILUndef.h"
#include "swift/SIL/TypeLowering.h"
#include "swift/SIL/DebugUtils.h"
#include "swift/SIL/InstructionUtils.h"
#include "swift/SIL/BasicBlockUtils.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include <deque>
using namespace swift;
static llvm::cl::opt<bool> EnableExpandAll("enable-expand-all",
llvm::cl::init(false));
/// Creates an increment on \p Ptr before insertion point \p InsertPt that
/// creates a strong_retain if \p Ptr has reference semantics itself or a
/// retain_value if \p Ptr is a non-trivial value without reference-semantics.
NullablePtr<SILInstruction>
swift::createIncrementBefore(SILValue Ptr, SILInstruction *InsertPt) {
// If we have a trivial type, just bail, there is no work to do.
if (Ptr->getType().isTrivial(InsertPt->getModule()))
return nullptr;
// Set up the builder we use to insert at our insertion point.
SILBuilder B(InsertPt);
auto Loc = RegularLocation::getAutoGeneratedLocation();
// If Ptr is refcounted itself, create the strong_retain and
// return.
if (Ptr->getType().isReferenceCounted(B.getModule())) {
if (Ptr->getType().is<UnownedStorageType>())
return B.createUnownedRetain(Loc, Ptr, B.getDefaultAtomicity());
else
return B.createStrongRetain(Loc, Ptr, B.getDefaultAtomicity());
}
// Otherwise, create the retain_value.
return B.createRetainValue(Loc, Ptr, B.getDefaultAtomicity());
}
/// Creates a decrement on \p Ptr before insertion point \p InsertPt that
/// creates a strong_release if \p Ptr has reference semantics itself or
/// a release_value if \p Ptr is a non-trivial value without reference-semantics.
NullablePtr<SILInstruction>
swift::createDecrementBefore(SILValue Ptr, SILInstruction *InsertPt) {
if (Ptr->getType().isTrivial(InsertPt->getModule()))
return nullptr;
// Setup the builder we will use to insert at our insertion point.
SILBuilder B(InsertPt);
auto Loc = RegularLocation::getAutoGeneratedLocation();
// If Ptr has reference semantics itself, create a strong_release.
if (Ptr->getType().isReferenceCounted(B.getModule())) {
if (Ptr->getType().is<UnownedStorageType>())
return B.createUnownedRelease(Loc, Ptr, B.getDefaultAtomicity());
else
return B.createStrongRelease(Loc, Ptr, B.getDefaultAtomicity());
}
// Otherwise create a release value.
return B.createReleaseValue(Loc, Ptr, B.getDefaultAtomicity());
}
/// \brief Perform a fast local check to see if the instruction is dead.
///
/// This routine only examines the state of the instruction at hand.
bool
swift::isInstructionTriviallyDead(SILInstruction *I) {
// At Onone, consider all uses, including the debug_info.
// This way, debug_info is preserved at Onone.
if (I->hasUsesOfAnyResult() &&
I->getFunction()->getEffectiveOptimizationMode() <=
OptimizationMode::NoOptimization)
return false;
if (!onlyHaveDebugUsesOfAllResults(I) || isa<TermInst>(I))
return false;
if (auto *BI = dyn_cast<BuiltinInst>(I)) {
// Although the onFastPath builtin has no side-effects we don't want to
// remove it.
if (BI->getBuiltinInfo().ID == BuiltinValueKind::OnFastPath)
return false;
return !BI->mayHaveSideEffects();
}
// condfail instructions that obviously can't fail are dead.
if (auto *CFI = dyn_cast<CondFailInst>(I))
if (auto *ILI = dyn_cast<IntegerLiteralInst>(CFI->getOperand()))
if (!ILI->getValue())
return true;
// mark_uninitialized is never dead.
if (isa<MarkUninitializedInst>(I))
return false;
if (isa<MarkUninitializedBehaviorInst>(I))
return false;
if (isa<DebugValueInst>(I) || isa<DebugValueAddrInst>(I))
return false;
// These invalidate enums so "write" memory, but that is not an essential
// operation so we can remove these if they are trivially dead.
if (isa<UncheckedTakeEnumDataAddrInst>(I))
return true;
if (!I->mayHaveSideEffects())
return true;
return false;
}
/// \brief Return true if this is a release instruction and the released value
/// is a part of a guaranteed parameter.
bool swift::isIntermediateRelease(SILInstruction *I,
EpilogueARCFunctionInfo *EAFI) {
// Check whether this is a release instruction.
if (!isa<StrongReleaseInst>(I) && !isa<ReleaseValueInst>(I))
return false;
// OK. we have a release instruction.
// Check whether this is a release on part of a guaranteed function argument.
SILValue Op = stripValueProjections(I->getOperand(0));
auto *Arg = dyn_cast<SILFunctionArgument>(Op);
if (!Arg)
return false;
// This is a release on a guaranteed parameter. Its not the final release.
if (Arg->hasConvention(SILArgumentConvention::Direct_Guaranteed))
return true;
// This is a release on an owned parameter and its not the epilogue release.
// Its not the final release.
auto Rel = EAFI->computeEpilogueARCInstructions(
EpilogueARCContext::EpilogueARCKind::Release, Arg);
if (Rel.size() && !Rel.count(I))
return true;
// Failed to prove anything.
return false;
}
namespace {
using CallbackTy = llvm::function_ref<void(SILInstruction *)>;
} // end anonymous namespace
void swift::
recursivelyDeleteTriviallyDeadInstructions(ArrayRef<SILInstruction *> IA,
bool Force, CallbackTy Callback) {
SILBasicBlock::iterator instIter;
recursivelyDeleteTriviallyDeadInstructions(IA, instIter, Force, Callback);
}
void swift::recursivelyDeleteTriviallyDeadInstructions(
ArrayRef<SILInstruction *> IA, SILBasicBlock::iterator &InstIter,
bool Force, CallbackTy Callback) {
// Delete these instruction and others that become dead after it's deleted.
llvm::SmallPtrSet<SILInstruction *, 8> DeadInsts;
for (auto I : IA) {
// If the instruction is not dead and force is false, do nothing.
if (Force || isInstructionTriviallyDead(I))
DeadInsts.insert(I);
}
llvm::SmallPtrSet<SILInstruction *, 8> NextInsts;
while (!DeadInsts.empty()) {
for (auto I : DeadInsts) {
// Call the callback before we mutate the to be deleted instruction in any
// way.
Callback(I);
// Check if any of the operands will become dead as well.
MutableArrayRef<Operand> Ops = I->getAllOperands();
for (Operand &Op : Ops) {
SILValue OpVal = Op.get();
if (!OpVal)
continue;
// Remove the reference from the instruction being deleted to this
// operand.
Op.drop();
// If the operand is an instruction that is only used by the instruction
// being deleted, delete it.
if (auto *OpValInst = OpVal->getDefiningInstruction())
if (!DeadInsts.count(OpValInst) &&
isInstructionTriviallyDead(OpValInst))
NextInsts.insert(OpValInst);
}
// If we have a function ref inst, we need to especially drop its function
// argument so that it gets a proper ref decrement.
auto *FRI = dyn_cast<FunctionRefInst>(I);
if (FRI && FRI->getReferencedFunction())
FRI->dropReferencedFunction();
}
for (auto I : DeadInsts) {
// This will remove this instruction and all its uses.
eraseFromParentWithDebugInsts(I, InstIter);
}
NextInsts.swap(DeadInsts);
NextInsts.clear();
}
}
/// \brief If the given instruction is dead, delete it along with its dead
/// operands.
///
/// \param I The instruction to be deleted.
/// \param Force If Force is set, don't check if the top level instruction is
/// considered dead - delete it regardless.
SILBasicBlock::iterator
swift::recursivelyDeleteTriviallyDeadInstructions(SILInstruction *I, bool Force,
CallbackTy Callback) {
SILBasicBlock::iterator nextI = std::next(I->getIterator());
ArrayRef<SILInstruction *> AI = ArrayRef<SILInstruction *>(I);
recursivelyDeleteTriviallyDeadInstructions(AI, nextI, Force, Callback);
return nextI;
}
void swift::eraseUsesOfInstruction(SILInstruction *Inst,
CallbackTy Callback) {
for (auto result : Inst->getResults()) {
while (!result->use_empty()) {
auto UI = result->use_begin();
auto *User = UI->getUser();
assert(User && "User should never be NULL!");
// If the instruction itself has any uses, recursively zap them so that
// nothing uses this instruction.
eraseUsesOfInstruction(User, Callback);
// Walk through the operand list and delete any random instructions that
// will become trivially dead when this instruction is removed.
for (auto &Op : User->getAllOperands()) {
if (auto *OpI = Op.get()->getDefiningInstruction()) {
// Don't recursively delete the instruction we're working on.
// FIXME: what if we're being recursively invoked?
if (OpI != Inst) {
Op.drop();
recursivelyDeleteTriviallyDeadInstructions(OpI, false, Callback);
}
}
}
Callback(User);
User->eraseFromParent();
}
}
}
void swift::
collectUsesOfValue(SILValue V, llvm::SmallPtrSetImpl<SILInstruction *> &Insts) {
for (auto UI = V->use_begin(), E = V->use_end(); UI != E; UI++) {
auto *User = UI->getUser();
// Instruction has been processed.
if (!Insts.insert(User).second)
continue;
// Collect the users of this instruction.
for (auto result : User->getResults())
collectUsesOfValue(result, Insts);
}
}
void swift::eraseUsesOfValue(SILValue V) {
llvm::SmallPtrSet<SILInstruction *, 4> Insts;
// Collect the uses.
collectUsesOfValue(V, Insts);
// Erase the uses, we can have instructions that become dead because
// of the removal of these instructions, leave to DCE to cleanup.
// Its not safe to do recursively delete here as some of the SILInstruction
// maybe tracked by this set.
for (auto I : Insts) {
I->replaceAllUsesOfAllResultsWithUndef();
I->eraseFromParent();
}
}
// Devirtualization of functions with covariant return types produces
// a result that is not an apply, but takes an apply as an
// argument. Attempt to dig the apply out from this result.
FullApplySite swift::findApplyFromDevirtualizedResult(SILValue V) {
if (auto Apply = FullApplySite::isa(V))
return Apply;
if (isa<UpcastInst>(V) || isa<EnumInst>(V) || isa<UncheckedRefCastInst>(V))
return findApplyFromDevirtualizedResult(
cast<SingleValueInstruction>(V)->getOperand(0));
return FullApplySite();
}
bool swift::mayBindDynamicSelf(SILFunction *F) {
if (!F->hasSelfMetadataParam())
return false;
SILValue MDArg = F->getSelfMetadataArgument();
for (Operand *MDUse : F->getSelfMetadataArgument()->getUses()) {
SILInstruction *MDUser = MDUse->getUser();
for (Operand &TypeDepOp : MDUser->getTypeDependentOperands()) {
if (TypeDepOp.get() == MDArg)
return true;
}
}
return false;
}
static SILValue skipAddrProjections(SILValue V) {
for (;;) {
switch (V->getKind()) {
case ValueKind::IndexAddrInst:
case ValueKind::IndexRawPointerInst:
case ValueKind::StructElementAddrInst:
case ValueKind::TupleElementAddrInst:
V = cast<SingleValueInstruction>(V)->getOperand(0);
break;
default:
return V;
}
}
llvm_unreachable("there is no escape from an infinite loop");
}
/// Check whether the \p addr is an address of a tail-allocated array element.
bool swift::isAddressOfArrayElement(SILValue addr) {
addr = stripAddressProjections(addr);
if (auto *MD = dyn_cast<MarkDependenceInst>(addr))
addr = stripAddressProjections(MD->getValue());
// High-level SIL: check for an get_element_address array semantics call.
if (auto *PtrToAddr = dyn_cast<PointerToAddressInst>(addr))
if (auto *SEI = dyn_cast<StructExtractInst>(PtrToAddr->getOperand())) {
ArraySemanticsCall Call(SEI->getOperand());
if (Call && Call.getKind() == ArrayCallKind::kGetElementAddress)
return true;
}
// Check for an tail-address (of an array buffer object).
if (isa<RefTailAddrInst>(skipAddrProjections(addr)))
return true;
return false;
}
/// Find a new position for an ApplyInst's FuncRef so that it dominates its
/// use. Not that FunctionRefInsts may be shared by multiple ApplyInsts.
void swift::placeFuncRef(ApplyInst *AI, DominanceInfo *DT) {
FunctionRefInst *FuncRef = cast<FunctionRefInst>(AI->getCallee());
SILBasicBlock *DomBB =
DT->findNearestCommonDominator(AI->getParent(), FuncRef->getParent());
if (DomBB == AI->getParent() && DomBB != FuncRef->getParent())
// Prefer to place the FuncRef immediately before the call. Since we're
// moving FuncRef up, this must be the only call to it in the block.
FuncRef->moveBefore(AI);
else
// Otherwise, conservatively stick it at the beginning of the block.
FuncRef->moveBefore(&*DomBB->begin());
}
/// \brief Add an argument, \p val, to the branch-edge that is pointing into
/// block \p Dest. Return a new instruction and do not erase the old
/// instruction.
TermInst *swift::addArgumentToBranch(SILValue Val, SILBasicBlock *Dest,
TermInst *Branch) {
SILBuilderWithScope Builder(Branch);
if (auto *CBI = dyn_cast<CondBranchInst>(Branch)) {
SmallVector<SILValue, 8> TrueArgs;
SmallVector<SILValue, 8> FalseArgs;
for (auto A : CBI->getTrueArgs())
TrueArgs.push_back(A);
for (auto A : CBI->getFalseArgs())
FalseArgs.push_back(A);
if (Dest == CBI->getTrueBB()) {
TrueArgs.push_back(Val);
assert(TrueArgs.size() == Dest->getNumArguments());
} else {
FalseArgs.push_back(Val);
assert(FalseArgs.size() == Dest->getNumArguments());
}
return Builder.createCondBranch(CBI->getLoc(), CBI->getCondition(), CBI->getTrueBB(), TrueArgs, CBI->getFalseBB(), FalseArgs, CBI->getTrueBBCount(), CBI->getFalseBBCount());
}
if (auto *BI = dyn_cast<BranchInst>(Branch)) {
SmallVector<SILValue, 8> Args;
for (auto A : BI->getArgs())
Args.push_back(A);
Args.push_back(Val);
assert(Args.size() == Dest->getNumArguments());
return Builder.createBranch(BI->getLoc(), BI->getDestBB(), Args);
}
llvm_unreachable("unsupported terminator");
}
SILLinkage swift::getSpecializedLinkage(SILFunction *F, SILLinkage L) {
if (hasPrivateVisibility(L) &&
!F->isSerialized()) {
// Specializations of private symbols should remain so, unless
// they were serialized, which can only happen when specializing
// definitions from a standard library built with -sil-serialize-all.
return SILLinkage::Private;
}
return SILLinkage::Shared;
}
/// Remove all instructions in the body of \p BB in safe manner by using
/// undef.
void swift::clearBlockBody(SILBasicBlock *BB) {
// Instructions in the dead block may be used by other dead blocks. Replace
// any uses of them with undef values.
while (!BB->empty()) {
// Grab the last instruction in the BB.
auto *Inst = &BB->back();
// Replace any still-remaining uses with undef values and erase.
Inst->replaceAllUsesOfAllResultsWithUndef();
Inst->eraseFromParent();
}
}
// Handle the mechanical aspects of removing an unreachable block.
void swift::removeDeadBlock(SILBasicBlock *BB) {
// Clear the body of BB.
clearBlockBody(BB);
// Now that the BB is empty, eliminate it.
BB->eraseFromParent();
}
/// Cast a value into the expected, ABI compatible type if necessary.
/// This may happen e.g. when:
/// - a type of the return value is a subclass of the expected return type.
/// - actual return type and expected return type differ in optionality.
/// - both types are tuple-types and some of the elements need to be casted.
///
/// If CheckOnly flag is set, then this function only checks if the
/// required casting is possible. If it is not possible, then None
/// is returned.
///
/// If CheckOnly is not set, then a casting code is generated and the final
/// casted value is returned.
///
/// NOTE: We intentionally combine the checking of the cast's handling possibility
/// and the transformation performing the cast in the same function, to avoid
/// any divergence between the check and the implementation in the future.
///
/// NOTE: The implementation of this function is very closely related to the
/// rules checked by SILVerifier::requireABICompatibleFunctionTypes.
SILValue swift::castValueToABICompatibleType(SILBuilder *B, SILLocation Loc,
SILValue Value,
SILType SrcTy, SILType DestTy) {
// No cast is required if types are the same.
if (SrcTy == DestTy)
return Value;
assert(SrcTy.isAddress() == DestTy.isAddress() &&
"Addresses aren't compatible with values");
if (SrcTy.isAddress() && DestTy.isAddress()) {
// Cast between two addresses and that's it.
return B->createUncheckedAddrCast(Loc, Value, DestTy);
}
// If both types are classes and dest is the superclass of src,
// simply perform an upcast.
if (DestTy.isExactSuperclassOf(SrcTy)) {
return B->createUpcast(Loc, Value, DestTy);
}
if (SrcTy.isHeapObjectReferenceType() &&
DestTy.isHeapObjectReferenceType()) {
return B->createUncheckedRefCast(Loc, Value, DestTy);
}
if (auto mt1 = SrcTy.getAs<AnyMetatypeType>()) {
if (auto mt2 = DestTy.getAs<AnyMetatypeType>()) {
if (mt1->getRepresentation() == mt2->getRepresentation()) {
// If B.Type needs to be casted to A.Type and
// A is a superclass of B, then it can be done by means
// of a simple upcast.
if (mt2.getInstanceType()->isExactSuperclassOf(
mt1.getInstanceType())) {
return B->createUpcast(Loc, Value, DestTy);
}
// Cast between two metatypes and that's it.
return B->createUncheckedBitCast(Loc, Value, DestTy);
}
}
}
// Check if src and dest types are optional.
auto OptionalSrcTy = SrcTy.getOptionalObjectType();
auto OptionalDestTy = DestTy.getOptionalObjectType();
// Both types are optional.
if (OptionalDestTy && OptionalSrcTy) {
// If both wrapped types are classes and dest is the superclass of src,
// simply perform an upcast.
if (OptionalDestTy.isExactSuperclassOf(OptionalSrcTy)) {
// Insert upcast.
return B->createUpcast(Loc, Value, DestTy);
}
// Unwrap the original optional value.
auto *SomeDecl = B->getASTContext().getOptionalSomeDecl();
auto *NoneBB = B->getFunction().createBasicBlock();
auto *SomeBB = B->getFunction().createBasicBlock();
auto *CurBB = B->getInsertionPoint()->getParent();
auto *ContBB = CurBB->split(B->getInsertionPoint());
ContBB->createPhiArgument(DestTy, ValueOwnershipKind::Owned);
SmallVector<std::pair<EnumElementDecl *, SILBasicBlock *>, 1> CaseBBs;
CaseBBs.push_back(std::make_pair(SomeDecl, SomeBB));
B->setInsertionPoint(CurBB);
B->createSwitchEnum(Loc, Value, NoneBB, CaseBBs);
// Handle the Some case.
B->setInsertionPoint(SomeBB);
SILValue UnwrappedValue = B->createUncheckedEnumData(Loc, Value,
SomeDecl);
// Cast the unwrapped value.
auto CastedUnwrappedValue =
castValueToABICompatibleType(B, Loc, UnwrappedValue,
OptionalSrcTy,
OptionalDestTy);
// Wrap into optional.
auto CastedValue = B->createOptionalSome(Loc, CastedUnwrappedValue, DestTy);
B->createBranch(Loc, ContBB, {CastedValue});
// Handle the None case.
B->setInsertionPoint(NoneBB);
CastedValue = B->createOptionalNone(Loc, DestTy);
B->createBranch(Loc, ContBB, {CastedValue});
B->setInsertionPoint(ContBB->begin());
return ContBB->getArgument(0);
}
// Src is not optional, but dest is optional.
if (!OptionalSrcTy && OptionalDestTy) {
auto OptionalSrcCanTy = OptionalType::get(SrcTy.getASTType())
->getCanonicalType();
auto LoweredOptionalSrcType = SILType::getPrimitiveObjectType(
OptionalSrcCanTy);
// Wrap the source value into an optional first.
SILValue WrappedValue = B->createOptionalSome(Loc, Value,
LoweredOptionalSrcType);
// Cast the wrapped value.
return castValueToABICompatibleType(B, Loc, WrappedValue,
WrappedValue->getType(),
DestTy);
}
// Handle tuple types.
// Extract elements, cast each of them, create a new tuple.
if (auto SrcTupleTy = SrcTy.getAs<TupleType>()) {
SmallVector<SILValue, 8> ExpectedTuple;
for (unsigned i = 0, e = SrcTupleTy->getNumElements(); i < e; i++) {
SILValue Element = B->createTupleExtract(Loc, Value, i);
// Cast the value if necessary.
Element = castValueToABICompatibleType(B, Loc, Element,
SrcTy.getTupleElementType(i),
DestTy.getTupleElementType(i));
ExpectedTuple.push_back(Element);
}
return B->createTuple(Loc, DestTy, ExpectedTuple);
}
// Function types are interchangeable if they're also ABI-compatible.
if (SrcTy.is<SILFunctionType>()) {
if (DestTy.is<SILFunctionType>()) {
assert(SrcTy.getAs<SILFunctionType>()->isNoEscape() ==
DestTy.getAs<SILFunctionType>()->isNoEscape() ||
SrcTy.getAs<SILFunctionType>()->getRepresentation() !=
SILFunctionType::Representation::Thick &&
"Swift thick functions that differ in escapeness are not ABI "
"compatible");
// Insert convert_function.
return B->createConvertFunction(Loc, Value, DestTy,
/*WithoutActuallyEscaping=*/false);
}
}
llvm::errs() << "Source type: " << SrcTy << "\n";
llvm::errs() << "Destination type: " << DestTy << "\n";
llvm_unreachable("Unknown combination of types for casting");
}
ProjectBoxInst *swift::getOrCreateProjectBox(AllocBoxInst *ABI, unsigned Index){
SILBasicBlock::iterator Iter(ABI);
Iter++;
assert(Iter != ABI->getParent()->end() &&
"alloc_box cannot be the last instruction of a block");
SILInstruction *NextInst = &*Iter;
if (auto *PBI = dyn_cast<ProjectBoxInst>(NextInst)) {
if (PBI->getOperand() == ABI && PBI->getFieldIndex() == Index)
return PBI;
}
SILBuilder B(NextInst);
return B.createProjectBox(ABI->getLoc(), ABI, Index);
}
//===----------------------------------------------------------------------===//
// String Concatenation Optimizer
//===----------------------------------------------------------------------===//
namespace {
/// This is a helper class that performs optimization of string literals
/// concatenation.
class StringConcatenationOptimizer {
/// Apply instruction being optimized.
ApplyInst *AI;
/// Builder to be used for creation of new instructions.
SILBuilder &Builder;
/// Left string literal operand of a string concatenation.
StringLiteralInst *SLILeft = nullptr;
/// Right string literal operand of a string concatenation.
StringLiteralInst *SLIRight = nullptr;
/// Function used to construct the left string literal.
FunctionRefInst *FRILeft = nullptr;
/// Function used to construct the right string literal.
FunctionRefInst *FRIRight = nullptr;
/// Apply instructions used to construct left string literal.
ApplyInst *AILeft = nullptr;
/// Apply instructions used to construct right string literal.
ApplyInst *AIRight = nullptr;
/// String literal conversion function to be used.
FunctionRefInst *FRIConvertFromBuiltin = nullptr;
/// Result type of a function producing the concatenated string literal.
SILValue FuncResultType;
/// Internal helper methods
bool extractStringConcatOperands();
void adjustEncodings();
APInt getConcatenatedLength();
bool isAscii() const;
public:
StringConcatenationOptimizer(ApplyInst *AI, SILBuilder &Builder)
: AI(AI), Builder(Builder) {}
/// Tries to optimize a given apply instruction if it is a
/// concatenation of string literals.
///
/// Returns a new instruction if optimization was possible.
SingleValueInstruction *optimize();
};
} // end anonymous namespace
/// Checks operands of a string concatenation operation to see if
/// optimization is applicable.
///
/// Returns false if optimization is not possible.
/// Returns true and initializes internal fields if optimization is possible.
bool StringConcatenationOptimizer::extractStringConcatOperands() {
auto *Fn = AI->getReferencedFunction();
if (!Fn)
return false;
if (AI->getNumArguments() != 3 || !Fn->hasSemanticsAttr("string.concat"))
return false;
// Left and right operands of a string concatenation operation.
AILeft = dyn_cast<ApplyInst>(AI->getOperand(1));
AIRight = dyn_cast<ApplyInst>(AI->getOperand(2));
if (!AILeft || !AIRight)
return false;
FRILeft = dyn_cast<FunctionRefInst>(AILeft->getCallee());
FRIRight = dyn_cast<FunctionRefInst>(AIRight->getCallee());
if (!FRILeft || !FRIRight)
return false;
auto *FRILeftFun = FRILeft->getReferencedFunction();
auto *FRIRightFun = FRIRight->getReferencedFunction();
if (FRILeftFun->getEffectsKind() >= EffectsKind::ReleaseNone ||
FRIRightFun->getEffectsKind() >= EffectsKind::ReleaseNone)
return false;
if (!FRILeftFun->hasSemanticsAttrs() || !FRIRightFun->hasSemanticsAttrs())
return false;
auto AILeftOperandsNum = AILeft->getNumOperands();
auto AIRightOperandsNum = AIRight->getNumOperands();
// makeUTF8 should have following parameters:
// (start: RawPointer, utf8CodeUnitCount: Word, isASCII: Int1)
if (!((FRILeftFun->hasSemanticsAttr("string.makeUTF8") &&
AILeftOperandsNum == 5) ||
(FRIRightFun->hasSemanticsAttr("string.makeUTF8") &&
AIRightOperandsNum == 5)))
return false;
SLILeft = dyn_cast<StringLiteralInst>(AILeft->getOperand(1));
SLIRight = dyn_cast<StringLiteralInst>(AIRight->getOperand(1));
if (!SLILeft || !SLIRight)
return false;
// Only UTF-8 and UTF-16 encoded string literals are supported by this
// optimization.
if (SLILeft->getEncoding() != StringLiteralInst::Encoding::UTF8 &&
SLILeft->getEncoding() != StringLiteralInst::Encoding::UTF16)
return false;
if (SLIRight->getEncoding() != StringLiteralInst::Encoding::UTF8 &&
SLIRight->getEncoding() != StringLiteralInst::Encoding::UTF16)
return false;
return true;
}
/// Ensures that both string literals to be concatenated use the same
/// UTF encoding. Converts UTF-8 into UTF-16 if required.
void StringConcatenationOptimizer::adjustEncodings() {
if (SLILeft->getEncoding() == SLIRight->getEncoding()) {
FRIConvertFromBuiltin = FRILeft;
if (SLILeft->getEncoding() == StringLiteralInst::Encoding::UTF8) {
FuncResultType = AILeft->getOperand(4);
} else {
FuncResultType = AILeft->getOperand(3);
}
return;
}
Builder.setCurrentDebugScope(AI->getDebugScope());
// If one of the string literals is UTF8 and another one is UTF16,
// convert the UTF8-encoded string literal into UTF16-encoding first.
if (SLILeft->getEncoding() == StringLiteralInst::Encoding::UTF8 &&
SLIRight->getEncoding() == StringLiteralInst::Encoding::UTF16) {
FuncResultType = AIRight->getOperand(3);
FRIConvertFromBuiltin = FRIRight;
// Convert UTF8 representation into UTF16.
SLILeft = Builder.createStringLiteral(AI->getLoc(), SLILeft->getValue(),
StringLiteralInst::Encoding::UTF16);
}
if (SLIRight->getEncoding() == StringLiteralInst::Encoding::UTF8 &&
SLILeft->getEncoding() == StringLiteralInst::Encoding::UTF16) {
FuncResultType = AILeft->getOperand(3);
FRIConvertFromBuiltin = FRILeft;
// Convert UTF8 representation into UTF16.
SLIRight = Builder.createStringLiteral(AI->getLoc(), SLIRight->getValue(),
StringLiteralInst::Encoding::UTF16);
}
// It should be impossible to have two operands with different
// encodings at this point.
assert(SLILeft->getEncoding() == SLIRight->getEncoding() &&
"Both operands of string concatenation should have the same encoding");
}
/// Computes the length of a concatenated string literal.
APInt StringConcatenationOptimizer::getConcatenatedLength() {
// Real length of string literals computed based on its contents.
// Length is in code units.
auto SLILenLeft = SLILeft->getCodeUnitCount();
(void) SLILenLeft;
auto SLILenRight = SLIRight->getCodeUnitCount();
(void) SLILenRight;
// Length of string literals as reported by string.make functions.
auto *LenLeft = dyn_cast<IntegerLiteralInst>(AILeft->getOperand(2));
auto *LenRight = dyn_cast<IntegerLiteralInst>(AIRight->getOperand(2));
// Real and reported length should be the same.
assert(SLILenLeft == LenLeft->getValue() &&
"Size of string literal in @_semantics(string.make) is wrong");
assert(SLILenRight == LenRight->getValue() &&
"Size of string literal in @_semantics(string.make) is wrong");
// Compute length of the concatenated literal.
return LenLeft->getValue() + LenRight->getValue();
}
/// Computes the isAscii flag of a concatenated UTF8-encoded string literal.
bool StringConcatenationOptimizer::isAscii() const{
// Add the isASCII argument in case of UTF8.
// IsASCII is true only if IsASCII of both literals is true.
auto *AsciiLeft = dyn_cast<IntegerLiteralInst>(AILeft->getOperand(3));
auto *AsciiRight = dyn_cast<IntegerLiteralInst>(AIRight->getOperand(3));
auto IsAsciiLeft = AsciiLeft->getValue() == 1;
auto IsAsciiRight = AsciiRight->getValue() == 1;
return IsAsciiLeft && IsAsciiRight;
}
SingleValueInstruction *StringConcatenationOptimizer::optimize() {
// Bail out if string literals concatenation optimization is
// not possible.
if (!extractStringConcatOperands())
return nullptr;
// Perform string literal encodings adjustments if needed.
adjustEncodings();
// Arguments of the new StringLiteralInst to be created.
SmallVector<SILValue, 4> Arguments;
// Encoding to be used for the concatenated string literal.
auto Encoding = SLILeft->getEncoding();
// Create a concatenated string literal.
Builder.setCurrentDebugScope(AI->getDebugScope());
auto LV = SLILeft->getValue();
auto RV = SLIRight->getValue();
auto *NewSLI =
Builder.createStringLiteral(AI->getLoc(), LV + Twine(RV), Encoding);
Arguments.push_back(NewSLI);
// Length of the concatenated literal according to its encoding.
auto *Len = Builder.createIntegerLiteral(
AI->getLoc(), AILeft->getOperand(2)->getType(), getConcatenatedLength());
Arguments.push_back(Len);
// isAscii flag for UTF8-encoded string literals.
if (Encoding == StringLiteralInst::Encoding::UTF8) {
bool IsAscii = isAscii();
auto ILType = AILeft->getOperand(3)->getType();
auto *Ascii =
Builder.createIntegerLiteral(AI->getLoc(), ILType, intmax_t(IsAscii));
Arguments.push_back(Ascii);
}
// Type.
Arguments.push_back(FuncResultType);
return Builder.createApply(AI->getLoc(), FRIConvertFromBuiltin,
SubstitutionMap(), Arguments,
false);
}
/// Top level entry point
SingleValueInstruction *
swift::tryToConcatenateStrings(ApplyInst *AI, SILBuilder &B) {
return StringConcatenationOptimizer(AI, B).optimize();
}
//===----------------------------------------------------------------------===//
// Closure Deletion
//===----------------------------------------------------------------------===//
static bool useDoesNotKeepClosureAlive(const SILInstruction *I) {
switch (I->getKind()) {
case SILInstructionKind::StrongRetainInst:
case SILInstructionKind::StrongReleaseInst:
case SILInstructionKind::CopyValueInst:
case SILInstructionKind::DestroyValueInst:
case SILInstructionKind::RetainValueInst:
case SILInstructionKind::ReleaseValueInst:
case SILInstructionKind::DebugValueInst:
return true;
default:
return false;
}
}
static bool useHasTransitiveOwnership(const SILInstruction *I) {
// convert_escape_to_noescape is used to convert to a @noescape function type.
// It does not change ownership of the function value.
return isa<ConvertEscapeToNoEscapeInst>(I);
}
static SILValue createLifetimeExtendedAllocStack(
SILBuilder &Builder, SILLocation Loc, SILValue Arg,
ArrayRef<SILBasicBlock *> ExitingBlocks, InstModCallbacks Callbacks) {
AllocStackInst *ASI = nullptr;
{
// Save our insert point and create a new alloc_stack in the initial BB and
// dealloc_stack in all exit blocks.
auto *OldInsertPt = &*Builder.getInsertionPoint();
Builder.setInsertionPoint(Builder.getFunction().begin()->begin());
ASI = Builder.createAllocStack(Loc, Arg->getType());
Callbacks.CreatedNewInst(ASI);
for (auto *BB : ExitingBlocks) {
Builder.setInsertionPoint(BB->getTerminator());
Callbacks.CreatedNewInst(Builder.createDeallocStack(Loc, ASI));
}
Builder.setInsertionPoint(OldInsertPt);
}
assert(ASI != nullptr);
// Then perform a copy_addr [take] [init] right after the partial_apply from
// the original address argument to the new alloc_stack that we have
// created.
Callbacks.CreatedNewInst(
Builder.createCopyAddr(Loc, Arg, ASI, IsTake, IsInitialization));
// Return the new alloc_stack inst that has the appropriate live range to
// destroy said values.
return ASI;
}
static bool shouldDestroyPartialApplyCapturedArg(SILValue Arg,
SILParameterInfo PInfo,
SILModule &M) {
// If we have a non-trivial type and the argument is passed in @inout, we do
// not need to destroy it here. This is something that is implicit in the
// partial_apply design that will be revisited when partial_apply is
// redesigned.
if (PInfo.isIndirectMutating())
return false;
// If we have a trivial type, we do not need to put in any extra releases.
if (Arg->getType().isTrivial(M))
return false;
// We handle all other cases.
return true;
}
// *HEY YOU, YES YOU, PLEASE READ*. Even though a textual partial apply is
// printed with the convention of the closed over function upon it, all
// non-inout arguments to a partial_apply are passed at +1. This includes
// arguments that will eventually be passed as guaranteed or in_guaranteed to
// the closed over function. This is because the partial apply is building up a
// boxed aggregate to send off to the closed over function. Of course when you
// call the function, the proper conventions will be used.
void swift::releasePartialApplyCapturedArg(SILBuilder &Builder, SILLocation Loc,
SILValue Arg, SILParameterInfo PInfo,
InstModCallbacks Callbacks) {
if (!shouldDestroyPartialApplyCapturedArg(Arg, PInfo, Builder.getModule()))
return;
// Otherwise, we need to destroy the argument. If we have an address, we
// insert a destroy_addr and return. Any live range issues must have been
// dealt with by our caller.
if (Arg->getType().isAddress()) {
// Then emit the destroy_addr for this arg
SILInstruction *NewInst = Builder.emitDestroyAddrAndFold(Loc, Arg);
Callbacks.CreatedNewInst(NewInst);
return;
}
// Otherwise, we have an object. We emit the most optimized form of release
// possible for that value.
// If we have qualified ownership, we should just emit a destroy value.
if (Arg->getFunction()->hasQualifiedOwnership()) {
Callbacks.CreatedNewInst(Builder.createDestroyValue(Loc, Arg));
return;
}
if (Arg->getType().hasReferenceSemantics()) {
auto U = Builder.emitStrongRelease(Loc, Arg);
if (U.isNull())
return;
if (auto *SRI = U.dyn_cast<StrongRetainInst *>()) {
Callbacks.DeleteInst(SRI);
return;
}
Callbacks.CreatedNewInst(U.get<StrongReleaseInst *>());
return;
}
auto U = Builder.emitReleaseValue(Loc, Arg);
if (U.isNull())
return;
if (auto *RVI = U.dyn_cast<RetainValueInst *>()) {
Callbacks.DeleteInst(RVI);
return;
}
Callbacks.CreatedNewInst(U.get<ReleaseValueInst *>());
}
/// For each captured argument of PAI, decrement the ref count of the captured
/// argument as appropriate at each of the post dominated release locations
/// found by Tracker.
static bool releaseCapturedArgsOfDeadPartialApply(PartialApplyInst *PAI,
ReleaseTracker &Tracker,
InstModCallbacks Callbacks) {
SILBuilderWithScope Builder(PAI);
SILLocation Loc = PAI->getLoc();
CanSILFunctionType PAITy =
PAI->getCallee()->getType().getAs<SILFunctionType>();
ArrayRef<SILParameterInfo> Params = PAITy->getParameters();
llvm::SmallVector<SILValue, 8> Args;
for (SILValue v : PAI->getArguments()) {
// If any of our arguments contain open existentials, bail. We do not
// support this for now so that we can avoid having to re-order stack
// locations (a larger change).
if (v->getType().hasOpenedExistential())
return false;
Args.emplace_back(v);
}
unsigned Delta = Params.size() - Args.size();
assert(Delta <= Params.size() && "Error, more Args to partial apply than "
"params in its interface.");
Params = Params.drop_front(Delta);
llvm::SmallVector<SILBasicBlock *, 2> ExitingBlocks;
PAI->getFunction()->findExitingBlocks(ExitingBlocks);
// Go through our argument list and create new alloc_stacks for each
// non-trivial address value. This ensures that the memory location that we
// are cleaning up has the same live range as the partial_apply. Otherwise, we
// may be inserting destroy_addr of alloc_stack that have already been passed
// to a dealloc_stack.
for (unsigned i : reversed(indices(Args))) {
SILValue Arg = Args[i];
SILParameterInfo PInfo = Params[i];
// If we are not going to destroy this partial_apply, continue.
if (!shouldDestroyPartialApplyCapturedArg(Arg, PInfo, Builder.getModule()))
continue;
// If we have an object, we will not have live range issues, just continue.
if (Arg->getType().isObject())
continue;
// Now that we know that we have a non-argument address, perform a take-init
// of Arg into a lifetime extended alloc_stack
Args[i] = createLifetimeExtendedAllocStack(Builder, Loc, Arg, ExitingBlocks,
Callbacks);
}
// Emit a destroy for each captured closure argument at each final release
// point.
for (auto *FinalRelease : Tracker.getFinalReleases()) {
Builder.setInsertionPoint(FinalRelease);
Builder.setCurrentDebugScope(FinalRelease->getDebugScope());
for (unsigned i : indices(Args)) {
SILValue Arg = Args[i];
SILParameterInfo Param = Params[i];
releasePartialApplyCapturedArg(Builder, Loc, Arg, Param, Callbacks);
}
}
return true;
}
/// TODO: Generalize this to general objects.
bool swift::tryDeleteDeadClosure(SingleValueInstruction *Closure,
InstModCallbacks Callbacks) {
// We currently only handle locally identified values that do not escape. We
// also assume that the partial apply does not capture any addresses.
if (!isa<PartialApplyInst>(Closure) && !isa<ThinToThickFunctionInst>(Closure))
return false;
// We only accept a user if it is an ARC object that can be removed if the
// object is dead. This should be expanded in the future. This also ensures
// that we are locally identified and non-escaping since we only allow for
// specific ARC users.
ReleaseTracker Tracker(useDoesNotKeepClosureAlive, useHasTransitiveOwnership);
// Find the ARC Users and the final retain, release.
if (!getFinalReleasesForValue(SILValue(Closure), Tracker))
return false;
// If we have a partial_apply, release each captured argument at each one of
// the final release locations of the partial apply.
if (auto *PAI = dyn_cast<PartialApplyInst>(Closure)) {
// If we can not decrement the ref counts of the dead partial apply for any
// reason, bail.
if (!releaseCapturedArgsOfDeadPartialApply(PAI, Tracker, Callbacks))
return false;
}
// Then delete all user instructions in reverse so that leaf uses are deleted
// first.
for (auto *User : reverse(Tracker.getTrackedUsers())) {
assert(User->getResults().empty() ||
useHasTransitiveOwnership(User) &&
"We expect only ARC operations without "
"results or a cast from escape to noescape without users");
Callbacks.DeleteInst(User);
}
// Finally delete the closure.
Callbacks.DeleteInst(Closure);
return true;
}
//===----------------------------------------------------------------------===//
// Value Lifetime
//===----------------------------------------------------------------------===//
void ValueLifetimeAnalysis::propagateLiveness() {
assert(LiveBlocks.empty() && "frontier computed twice");
auto DefBB = DefValue->getParentBlock();
llvm::SmallVector<SILBasicBlock *, 64> Worklist;
int NumUsersBeforeDef = 0;
// Find the initial set of blocks where the value is live, because
// it is used in those blocks.
for (SILInstruction *User : UserSet) {
SILBasicBlock *UserBlock = User->getParent();
if (LiveBlocks.insert(UserBlock))
Worklist.push_back(UserBlock);
// A user in the DefBB could potentially be located before the DefValue.
if (UserBlock == DefBB)
NumUsersBeforeDef++;
}
// Don't count any users in the DefBB which are actually located _after_
// the DefValue.
auto InstIter = DefValue->getIterator();
while (NumUsersBeforeDef > 0 && ++InstIter != DefBB->end()) {
if (UserSet.count(&*InstIter))
NumUsersBeforeDef--;
}
// Now propagate liveness backwards until we hit the block that defines the
// value.
while (!Worklist.empty()) {
auto *BB = Worklist.pop_back_val();
// Don't go beyond the definition.
if (BB == DefBB && NumUsersBeforeDef == 0)
continue;
for (SILBasicBlock *Pred : BB->getPredecessorBlocks()) {
// If it's already in the set, then we've already queued and/or
// processed the predecessors.
if (LiveBlocks.insert(Pred))
Worklist.push_back(Pred);
}
}
}
SILInstruction *ValueLifetimeAnalysis:: findLastUserInBlock(SILBasicBlock *BB) {
// Walk backwards in BB looking for last use of the value.
for (auto II = BB->rbegin(); II != BB->rend(); ++II) {
assert(DefValue != &*II && "Found def before finding use!");
if (UserSet.count(&*II))
return &*II;
}
llvm_unreachable("Expected to find use of value in block!");
}
bool ValueLifetimeAnalysis::computeFrontier(Frontier &Fr, Mode mode,
DeadEndBlocks *DEBlocks) {
assert(!isAliveAtBeginOfBlock(DefValue->getFunction()->getEntryBlock()) &&
"Can't compute frontier for def which does not dominate all uses");
bool NoCriticalEdges = true;
// Exit-blocks from the lifetime region. The value is live at the end of
// a predecessor block but not in the frontier block itself.
llvm::SmallSetVector<SILBasicBlock *, 16> FrontierBlocks;
// Blocks where the value is live at the end of the block and which have
// a frontier block as successor.
llvm::SmallSetVector<SILBasicBlock *, 16> LiveOutBlocks;
/// The lifetime ends if we have a live block and a not-live successor.
for (SILBasicBlock *BB : LiveBlocks) {
if (DEBlocks && DEBlocks->isDeadEnd(BB))
continue;
bool LiveInSucc = false;
bool DeadInSucc = false;
for (const SILSuccessor &Succ : BB->getSuccessors()) {
if (isAliveAtBeginOfBlock(Succ)) {
LiveInSucc = true;
} else if (!DEBlocks || !DEBlocks->isDeadEnd(Succ)) {
DeadInSucc = true;
}
}
if (!LiveInSucc) {
// The value is not live in any of the successor blocks. This means the
// block contains a last use of the value. The next instruction after
// the last use is part of the frontier.
SILInstruction *LastUser = findLastUserInBlock(BB);
if (!isa<TermInst>(LastUser)) {
Fr.push_back(&*std::next(LastUser->getIterator()));
continue;
}
// In case the last user is a TermInst we add all successor blocks to the
// frontier (see below).
assert(DeadInSucc && "The final using TermInst must have successors");
}
if (DeadInSucc) {
if (mode == UsersMustPostDomDef)
return false;
// The value is not live in some of the successor blocks.
LiveOutBlocks.insert(BB);
for (const SILSuccessor &Succ : BB->getSuccessors()) {
if (!isAliveAtBeginOfBlock(Succ)) {
// It's an "exit" edge from the lifetime region.
FrontierBlocks.insert(Succ);
}
}
}
}
// Handle "exit" edges from the lifetime region.
llvm::SmallPtrSet<SILBasicBlock *, 16> UnhandledFrontierBlocks;
for (SILBasicBlock *FrontierBB: FrontierBlocks) {
assert(mode != UsersMustPostDomDef);
bool needSplit = false;
// If the value is live only in part of the predecessor blocks we have to
// split those predecessor edges.
for (SILBasicBlock *Pred : FrontierBB->getPredecessorBlocks()) {
if (!LiveOutBlocks.count(Pred)) {
needSplit = true;
break;
}
}
if (needSplit) {
if (mode == DontModifyCFG)
return false;
// We need to split the critical edge to create a frontier instruction.
UnhandledFrontierBlocks.insert(FrontierBB);
} else {
// The first instruction of the exit-block is part of the frontier.
Fr.push_back(&*FrontierBB->begin());
}
}
// Split critical edges from the lifetime region to not yet handled frontier
// blocks.
for (SILBasicBlock *FrontierPred : LiveOutBlocks) {
assert(mode != UsersMustPostDomDef);
auto *T = FrontierPred->getTerminator();
// Cache the successor blocks because splitting critical edges invalidates
// the successor list iterator of T.
llvm::SmallVector<SILBasicBlock *, 4> SuccBlocks;
for (const SILSuccessor &Succ : T->getSuccessors())
SuccBlocks.push_back(Succ);
for (unsigned i = 0, e = SuccBlocks.size(); i != e; ++i) {
if (UnhandledFrontierBlocks.count(SuccBlocks[i])) {
assert(mode == AllowToModifyCFG);
assert(isCriticalEdge(T, i) && "actually not a critical edge?");
SILBasicBlock *NewBlock = splitEdge(T, i);
// The single terminator instruction is part of the frontier.
Fr.push_back(&*NewBlock->begin());
NoCriticalEdges = false;
}
}
}
return NoCriticalEdges;
}
bool ValueLifetimeAnalysis::isWithinLifetime(SILInstruction *Inst) {
SILBasicBlock *BB = Inst->getParent();
// Check if the value is not live anywhere in Inst's block.
if (!LiveBlocks.count(BB))
return false;
for (const SILSuccessor &Succ : BB->getSuccessors()) {
// If the value is live at the beginning of any successor block it is also
// live at the end of BB and therefore Inst is definitely in the lifetime
// region (Note that we don't check in upward direction against the value's
// definition).
if (isAliveAtBeginOfBlock(Succ))
return true;
}
// The value is live in the block but not at the end of the block. Check if
// Inst is located before (or at) the last use.
for (auto II = BB->rbegin(); II != BB->rend(); ++II) {
if (UserSet.count(&*II)) {
return true;
}
if (Inst == &*II)
return false;
}
llvm_unreachable("Expected to find use of value in block!");
}
void ValueLifetimeAnalysis::dump() const {
llvm::errs() << "lifetime of def: " << *DefValue;
for (SILInstruction *Use : UserSet) {
llvm::errs() << " use: " << *Use;
}
llvm::errs() << " live blocks:";
for (SILBasicBlock *BB : LiveBlocks) {
llvm::errs() << ' ' << BB->getDebugID();
}
llvm::errs() << '\n';
}
// FIXME: Remove this. SILCloner should not create critical edges.
bool BasicBlockCloner::splitCriticalEdges(DominanceInfo *DT,
SILLoopInfo *LI) {
bool changed = false;
// Remove any critical edges that the EdgeThreadingCloner may have
// accidentally created.
for (unsigned succIdx = 0, succEnd = origBB->getSuccessors().size();
succIdx != succEnd; ++succIdx) {
if (nullptr != splitCriticalEdge(origBB->getTerminator(), succIdx, DT, LI))
changed |= true;
}
for (unsigned succIdx = 0, succEnd = getNewBB()->getSuccessors().size();
succIdx != succEnd; ++succIdx) {
auto *newBB =
splitCriticalEdge(getNewBB()->getTerminator(), succIdx, DT, LI);
changed |= (newBB != nullptr);
}
return changed;
}
bool swift::simplifyUsers(SingleValueInstruction *I) {
bool Changed = false;
for (auto UI = I->use_begin(), UE = I->use_end(); UI != UE; ) {
SILInstruction *User = UI->getUser();
++UI;
auto SVI = dyn_cast<SingleValueInstruction>(User);
if (!SVI) continue;
SILValue S = simplifyInstruction(SVI);
if (!S)
continue;
replaceAllSimplifiedUsesAndErase(SVI, S);
Changed = true;
}
return Changed;
}
/// True if a type can be expanded
/// without a significant increase to code size.
bool swift::shouldExpand(SILModule &Module, SILType Ty) {
if (Ty.isAddressOnly(Module)) {
return false;
}
if (EnableExpandAll) {
return true;
}
unsigned numFields = Module.Types.countNumberOfFields(Ty);
if (numFields > 6) {
return false;
}
return true;
}
/// Some support functions for the global-opt and let-properties-opts
/// Check if a given type is a simple type, i.e. a builtin
/// integer or floating point type or a struct/tuple whose members
/// are of simple types.
/// TODO: Cache the "simple" flag for types to avoid repeating checks.
bool swift::isSimpleType(SILType SILTy, SILModule& Module) {
// Classes can never be initialized statically at compile-time.
if (SILTy.getClassOrBoundGenericClass()) {
return false;
}
if (!SILTy.isTrivial(Module))
return false;
return true;
}
// Encapsulate the state used for recursive analysis of a static
// initializer. Discover all the instruction in a use-def graph and return them
// in topological order.
//
// TODO: We should have a DFS utility for this sort of thing so it isn't
// recursive.
class StaticInitializerAnalysis {
SmallVectorImpl<SILInstruction *> &postOrderInstructions;
llvm::SmallDenseSet<SILValue, 8> visited;
int recursionLevel = 0;
public:
StaticInitializerAnalysis(
SmallVectorImpl<SILInstruction *> &postOrderInstructions)
: postOrderInstructions(postOrderInstructions) {}
// Perform a recursive DFS on on the use-def graph rooted at `V`. Insert
// values in the `visited` set in preorder. Insert values in
// `postOrderInstructions` in postorder so that the instructions are
// topologically def-use ordered (in execution order).
bool analyze(SILValue RootValue) {
return recursivelyAnalyzeOperand(RootValue);
}
protected:
bool recursivelyAnalyzeOperand(SILValue V) {
if (!visited.insert(V).second)
return true;
if (++recursionLevel > 50)
return false;
// TODO: For multi-result instructions, we could simply insert all result
// values in the visited set here.
auto *I = dyn_cast<SingleValueInstruction>(V);
if (!I)
return false;
if (!recursivelyAnalyzeInstruction(I))
return false;
postOrderInstructions.push_back(I);
--recursionLevel;
return true;
}
bool recursivelyAnalyzeInstruction(SILInstruction *I) {
if (auto *SI = dyn_cast<StructInst>(I)) {
// If it is not a struct which is a simple type, bail.
if (!isSimpleType(SI->getType(), SI->getModule()))
return false;
return llvm::all_of(SI->getAllOperands(), [&](Operand &Op) -> bool {
return recursivelyAnalyzeOperand(Op.get());
});
}
if (auto *TI = dyn_cast<TupleInst>(I)) {
// If it is not a tuple which is a simple type, bail.
if (!isSimpleType(TI->getType(), TI->getModule()))
return false;
return llvm::all_of(TI->getAllOperands(), [&](Operand &Op) -> bool {
return recursivelyAnalyzeOperand(Op.get());
});
}
if (auto *bi = dyn_cast<BuiltinInst>(I)) {
switch (bi->getBuiltinInfo().ID) {
case BuiltinValueKind::FPTrunc:
if (auto *LI = dyn_cast<LiteralInst>(bi->getArguments()[0])) {
return recursivelyAnalyzeOperand(LI);
}
return false;
default:
return false;
}
}
return isa<IntegerLiteralInst>(I) || isa<FloatLiteralInst>(I)
|| isa<StringLiteralInst>(I);
}
};
/// Check if the value of V is computed by means of a simple initialization.
/// Populate `forwardInstructions` with references to all the instructions
/// that participate in the use-def graph required to compute `V`. The
/// instructions will be in def-use topological order.
bool swift::analyzeStaticInitializer(
SILValue V, SmallVectorImpl<SILInstruction *> &forwardInstructions) {
return StaticInitializerAnalysis(forwardInstructions).analyze(V);
}
/// Replace load sequence which may contain
/// a chain of struct_element_addr followed by a load.
/// The sequence is traversed inside out, i.e.
/// starting with the innermost struct_element_addr
/// Move into utils.
///
/// FIXME: this utility does not make sense as an API. How can the caller
/// guarantee that the only uses of `I` are struct_element_addr and
/// tuple_element_addr?
void swift::replaceLoadSequence(SILInstruction *I,
SILValue Value,
SILBuilder &B) {
if (auto *LI = dyn_cast<LoadInst>(I)) {
LI->replaceAllUsesWith(Value);
return;
}
// It is a series of struct_element_addr followed by load.
if (auto *SEAI = dyn_cast<StructElementAddrInst>(I)) {
auto *SEI = B.createStructExtract(SEAI->getLoc(), Value, SEAI->getField());
for (auto SEAIUse : SEAI->getUses()) {
replaceLoadSequence(SEAIUse->getUser(), SEI, B);
}
return;
}
if (auto *TEAI = dyn_cast<TupleElementAddrInst>(I)) {
auto *TEI = B.createTupleExtract(TEAI->getLoc(), Value, TEAI->getFieldNo());
for (auto TEAIUse : TEAI->getUses()) {
replaceLoadSequence(TEAIUse->getUser(), TEI, B);
}
return;
}
if (auto *BA = dyn_cast<BeginAccessInst>(I)) {
for (auto Use : BA->getUses()) {
replaceLoadSequence(Use->getUser(), Value, B);
}
return;
}
// Incidental uses of an addres are meaningless with regard to the loaded
// value.
if (isIncidentalUse(I) || isa<BeginUnpairedAccessInst>(I))
return;
llvm_unreachable("Unknown instruction sequence for reading from a global");
}
/// Are the callees that could be called through Decl statically
/// knowable based on the Decl and the compilation mode?
bool swift::calleesAreStaticallyKnowable(SILModule &M, SILDeclRef Decl) {
if (Decl.isForeign)
return false;
const DeclContext *AssocDC = M.getAssociatedContext();
if (!AssocDC)
return false;
auto *AFD = Decl.getAbstractFunctionDecl();
assert(AFD && "Expected abstract function decl!");
// Only handle members defined within the SILModule's associated context.
if (!AFD->isChildContextOf(AssocDC))
return false;
if (AFD->isDynamic())
return false;
if (!AFD->hasAccess())
return false;
// Only consider 'private' members, unless we are in whole-module compilation.
switch (AFD->getEffectiveAccess()) {
case AccessLevel::Open:
return false;
case AccessLevel::Public:
if (isa<ConstructorDecl>(AFD)) {
// Constructors are special: a derived class in another module can
// "override" a constructor if its class is "open", although the
// constructor itself is not open.
auto *ND = AFD->getDeclContext()->getSelfNominalTypeDecl();
if (ND->getEffectiveAccess() == AccessLevel::Open)
return false;
}
LLVM_FALLTHROUGH;
case AccessLevel::Internal:
return M.isWholeModule();
case AccessLevel::FilePrivate:
case AccessLevel::Private:
return true;
}
llvm_unreachable("Unhandled access level in switch.");
}
void StaticInitCloner::add(SILInstruction *InitVal) {
// Don't schedule an instruction twice for cloning.
if (NumOpsToClone.count(InitVal) != 0)
return;
ArrayRef<Operand> Ops = InitVal->getAllOperands();
NumOpsToClone[InitVal] = Ops.size();
if (Ops.empty()) {
// It's an instruction without operands, e.g. a literal. It's ready to be
// cloned first.
ReadyToClone.push_back(InitVal);
} else {
// Recursively add all operands.
for (const Operand &Op : Ops) {
add(cast<SingleValueInstruction>(Op.get()));
}
}
}
SingleValueInstruction *
StaticInitCloner::clone(SingleValueInstruction *InitVal) {
assert(NumOpsToClone.count(InitVal) != 0 && "InitVal was not added");
// Find the right order to clone: all operands of an instruction must be
// cloned before the instruction itself.
while (!ReadyToClone.empty()) {
SILInstruction *I = ReadyToClone.pop_back_val();
// Clone the instruction into the SILGlobalVariable
visit(I);
// Check if users of I can now be cloned.
for (SILValue result : I->getResults()) {
for (Operand *Use : result->getUses()) {
SILInstruction *User = Use->getUser();
if (NumOpsToClone.count(User) != 0 && --NumOpsToClone[User] == 0)
ReadyToClone.push_back(User);
}
}
}
return cast<SingleValueInstruction>(getMappedValue(InitVal));
}
Optional<FindLocalApplySitesResult>
swift::findLocalApplySites(FunctionRefInst *FRI) {
SmallVector<Operand *, 32> worklist(FRI->use_begin(), FRI->use_end());
Optional<FindLocalApplySitesResult> f;
f.emplace();
// Optimistically state that we have no escapes before our def-use dataflow.
f->escapes = false;
while (!worklist.empty()) {
auto *op = worklist.pop_back_val();
auto *user = op->getUser();
// If we have a full apply site as our user.
if (auto apply = FullApplySite::isa(user)) {
if (apply.getCallee() == op->get()) {
f->fullApplySites.push_back(apply);
continue;
}
}
// If we have a partial apply as a user, start tracking it, but also look at
// its users.
if (auto *pai = dyn_cast<PartialApplyInst>(user)) {
if (pai->getCallee() == op->get()) {
// Track the partial apply that we saw so we can potentially eliminate
// dead closure arguments.
f->partialApplySites.push_back(pai);
// Look to see if we can find a full application of this partial apply
// as well.
copy(pai->getUses(), std::back_inserter(worklist));
continue;
}
}
// Otherwise, see if we have any function casts to look through...
switch (user->getKind()) {
case SILInstructionKind::ThinToThickFunctionInst:
case SILInstructionKind::ConvertFunctionInst:
case SILInstructionKind::ConvertEscapeToNoEscapeInst:
copy(cast<SingleValueInstruction>(user)->getUses(),
std::back_inserter(worklist));
continue;
// Look through any reference count instructions since these are not
// escapes:
case SILInstructionKind::CopyValueInst:
copy(cast<CopyValueInst>(user)->getUses(), std::back_inserter(worklist));
continue;
case SILInstructionKind::StrongRetainInst:
case SILInstructionKind::StrongReleaseInst:
case SILInstructionKind::RetainValueInst:
case SILInstructionKind::ReleaseValueInst:
case SILInstructionKind::DestroyValueInst:
continue;
default:
break;
}
// But everything else is considered an escape.
f->escapes = true;
}
// If we did escape and didn't find any apply sites, then we have no
// information for our users that is interesting.
if (f->escapes && f->partialApplySites.empty() && f->fullApplySites.empty())
return None;
return f;
}